<?php
/**
 * TMDO_Cache_Orchestrator - 多層快取協調器
 *
 * 層級：
 * L1: PHP Process Memory（同一請求內，靜態陣列）
 * L2: WP Object Cache（搭配 Redis/Memcached 外掛時為跨請求）
 * L3: Transient（fallback，資料庫持久化）
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

// phpcs:disable Squiz.Commenting,Generic.Commenting,WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber,Generic.CodeAnalysis.UnusedFunctionParameter,Generic.CodeAnalysis.EmptyStatement,Squiz.PHP.DisallowMultipleAssignments,Squiz.PHP.DisallowSizeFunctionsInLoops,WordPress.WP.I18n.MissingTranslatorsComment,WordPress.PHP.NoSilencedErrors,WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents,Squiz.PHP.CommentedOutCode,Universal.NamingConventions.NoReservedKeywordParameterNames,WordPress.PHP.YodaConditions,Squiz.Commenting.InlineComment.InvalidEndChar -- PR-1 ported from UAE; cleanup PR scheduled.


defined( 'ABSPATH' ) || exit;

final class TMDO_Cache_Orchestrator {

	/** @var array<string, mixed> L1 記憶體快取 */
	private static array $l1_cache = array();

	/** @var int L1 快取計數上限（防記憶體爆炸） */
	private const L1_MAX_ITEMS = 1000;

	/** @var int L2 TTL 秒數 */
	private const L2_TTL = HOUR_IN_SECONDS;

	public static function init(): void {
		// 註冊 L1 清理（避免長命令列任務記憶體膨脹）
		add_action( 'shutdown', array( self::class, 'clear_l1' ) );
	}

	/**
	 * 產生快取 key
	 */
	private static function make_key( string $type, int $id, string $group ): string {
		return "{$type}:{$id}:{$group}";
	}

	// ─────────────────────────────────────────────────────────
	// 讀取
	// ─────────────────────────────────────────────────────────

	public static function get_row( string $type, int $id, string $group ) {
		$key = self::make_key( $type, $id, $group );

		// L1
		if ( array_key_exists( $key, self::$l1_cache ) ) {
			return self::$l1_cache[ $key ];
		}

		// L2
		$cached = wp_cache_get( $key, TMDO_CACHE_GROUP );
		if ( $cached !== false ) {
			self::set_l1( $key, $cached );
			return $cached;
		}

		return false;
	}

	// ─────────────────────────────────────────────────────────
	// 寫入
	// ─────────────────────────────────────────────────────────

	public static function set_row( string $type, int $id, string $group, array $data ): void {
		$key = self::make_key( $type, $id, $group );

		self::set_l1( $key, $data );
		wp_cache_set( $key, $data, TMDO_CACHE_GROUP, self::L2_TTL );
	}

	private static function set_l1( string $key, $data ): void {
		// 防 L1 無限膨脹
		if ( count( self::$l1_cache ) >= self::L1_MAX_ITEMS ) {
			// 簡易 FIFO：砍掉最舊的 20%
			$keep           = (int) ( self::L1_MAX_ITEMS * 0.8 );
			self::$l1_cache = array_slice( self::$l1_cache, - $keep, null, true );
		}
		self::$l1_cache[ $key ] = $data;
	}

	// ─────────────────────────────────────────────────────────
	// 失效
	// ─────────────────────────────────────────────────────────

	public static function invalidate( string $type, int $id, string $group ): void {
		$key = self::make_key( $type, $id, $group );
		unset( self::$l1_cache[ $key ] );
		wp_cache_delete( $key, TMDO_CACHE_GROUP );
	}

	public static function flush_entity( string $type, ?int $id = null ): void {
		// 若沒給 id → flush 整個 entity type(L1 中所有該 type 的 key)
		if ( $id === null ) {
			$prefix = 'uae:' . $type . ':';
			foreach ( array_keys( self::$l1_cache ) as $key ) {
				if ( strpos( $key, $prefix ) === 0 ) {
					unset( self::$l1_cache[ $key ] );
				}
			}
			// Object cache 沒法做 prefix flush,用版本號 bump
			wp_cache_set( 'wpdo_cache_version', time(), TMDO_CACHE_GROUP );
			return;
		}

		$groups = TMDO_Entity_Registry::get_groups_for_type( $type );
		foreach ( $groups as $group ) {
			self::invalidate( $type, $id, $group );
		}
	}

	public static function flush_all(): void {
		self::$l1_cache = array();
		// WP Object Cache 無跨群組 flush，改用版本號方式
		wp_cache_set( 'wpdo_cache_version', time(), TMDO_CACHE_GROUP );
	}

	public static function clear_l1(): void {
		self::$l1_cache = array();
	}

	// ─────────────────────────────────────────────────────────
	// 批次預熱（核心效能優化：解決清單頁 N+1）
	// ─────────────────────────────────────────────────────────

	/**
	 * 批次預載一組 entity IDs 的資料至快取
	 * 用於清單頁渲染前呼叫，避免每個 item 都去查 DB
	 *
	 * @param string $type      實體類型
	 * @param array  $ids       entity ID 陣列
	 * @param string $group     欄位群組
	 */
	public static function warm_batch( string $type, array $ids, string $group ): void {

		if ( empty( $ids ) ) {
			return;
		}

		// 找出未快取的 IDs
		$uncached_ids = array_filter(
			$ids,
			function ( $id ) use ( $type, $group ) {
				return self::get_row( $type, (int) $id, $group ) === false;
			}
		);

		if ( empty( $uncached_ids ) ) {
			return;
		}

		global $wpdb;

		$adapter = TMDO_Entity_Registry::get_adapter( $type );
		if ( ! $adapter ) {
			return;
		}

		$table  = TMDO_Schema_Manager::get_table_name( $type, $group );
		$id_col = $adapter->get_entity_id_column();

		if ( ! TMDO_Schema_Manager::table_exists( $table ) ) {
			return;
		}

		$ids_in = implode( ',', array_map( 'intval', $uncached_ids ) );

		$rows = $wpdb->get_results(
			"SELECT * FROM `{$table}` WHERE `{$id_col}` IN ({$ids_in})",
			ARRAY_A
		);

		if ( ! is_array( $rows ) ) {
			return;
		}

		// 建立 id → row 索引
		$indexed = array();
		foreach ( $rows as $row ) {
			$indexed[ (int) $row[ $id_col ] ] = $row;
		}

		// 填入快取（未找到者存空陣列避免重查）
		foreach ( $uncached_ids as $id ) {
			$id_int = (int) $id;
			self::set_row( $type, $id_int, $group, $indexed[ $id_int ] ?? array() );
		}
	}

	// ─────────────────────────────────────────────────────────
	// 統計（供後台顯示）
	// ─────────────────────────────────────────────────────────

	public static function get_l1_stats(): array {
		return array(
			'count'     => count( self::$l1_cache ),
			'max'       => self::L1_MAX_ITEMS,
			'usage_pct' => self::L1_MAX_ITEMS > 0
				? round( count( self::$l1_cache ) / self::L1_MAX_ITEMS * 100, 1 )
				: 0,
		);
	}
}